HEREDITY OF WILDNESS AND SAVAGENESS IN MICE 13 



The 1 1 wild mice whicii were captured and used for breeding 

 purposes in this study were, with the exception of mouse 472 cf , 

 full-grown when caught. This mouse was judged from 6 to 

 8 weeks old. All of these mice were tested several times for 

 wildness and savageness and in each test manifested the highest 

 grades. The last test occurred when the time of captivity 

 varied from 1 to 6 months. Each received a grade of 5 for 

 wildness and savageness except two (nos. 225 9 and 474 c^), 

 which were graded 4 in savageness. Although it was neces- 

 sary to handle these mice when weaning their young or chang- 

 ing their mates, there was during this handling no observation 

 of any behavior which would tend to indicate that their wild- 

 ness or savageness had decreased to any appreciable degree 

 even after they had been in captivity from one to two years. 

 However, when not being handled there was a very noticeable 

 difference in the degree of wildness. Instead of scurrying to 

 their nest as they did when the experimenter entered the room 

 during their early captivity, later they would, as a rule, re- 

 main in the open and continue eating, but it was never possible 

 to persuade them to come to the front of the cage to secure a 

 bit of food from the experimenter's fingers. 



The 12 wild mice, nos. 510 to 521 inclusive, were raised in 

 the laboratory and were tested five or six times in the same 

 manner and at regular intervals as the mice of table 2. A 

 summary of the results of these tests are presented in tables 

 15 and 16. These mice were chiefly used in matings with the 

 tame mice obtained from Miss Lathrop. 



Although no more crosses were made between the mice from 

 the Bussey Institute and the wild individuals after the dis- 

 covery of the apparent trace of wild blood, the series begun 

 by them was continued and the results will be presented in 

 this study. These results, however, will be summarized in 

 separate tables except in such cases where the information to 

 be noted is equally significant in each series. 



To avoid any confusion which might otherwise arise the 

 series from the crosses of Bussey Institute mice with wild mice 

 will be termed Series A, and the first, second, and third hybrid 

 generations of this series will be designated, Fia, F2a, and Fsa, 

 respectively. Likewise the series from crossing the tame mice 

 from Miss Lathrop with wild mice will be termed Series B, 

 and the hybrid generations. Fib, F2b, and Fab. 



